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Differentiation of Pathogenic and Nonpathogenic Escherichia coli Isolated from Poultry

B. Panigrahy and Ling Yushen
Avian Diseases
Vol. 34, No. 4 (Oct. - Dec., 1990), pp. 941-943
DOI: 10.2307/1591387
Stable URL: http://www.jstor.org/stable/1591387
Page Count: 3
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Differentiation of Pathogenic and Nonpathogenic Escherichia coli Isolated from Poultry
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Abstract

Twenty-one isolates of Escherichia coli recovered from chickens and turkeys were evaluated for pathogenicity in 1-week-old chicks. Fifteen produced coli-septicemia (pathogenic) and six were innocuous (nonpathogenic). Both pathogenic and nonpathogenic E. coli were tested for their ability to selectively absorb Congo red (CR) dye incorporated into agar medium. Eight of 15 pathogenic E. coli (somatic antigen types O1, O78, O11, O88, and OX9) absorbed the dye and produced red colonies (CR+) between 48 to 72 hours of incubation. All serotypes of E. coli with homologous somatic antigen O78 were CR+, while those of O2 antigen were CR- (white colonies). Five of six nonpathogenic E. coli also were CR+. In contrast to pathogenic E. coli, however, nonpathogenic isolates absorbed CR early, between 18 to 24 hours of incubation. Although CR dye binding did not correlate well with pathogenicity, it may be an identifiable property of some serotypes of E. coli. /// Usando pollos de una semana de edad, se evaluó la patogenicidad de 21 cepas de Escherichia coli obtenidas de pollos y pavos. Quince cepas produjeron colisepticemia (patógenas) y seis resultaron inocuas (apatógenas). Se evaluó la capacidad tanto de las cepas patógenas como la de las apatógenas para absorber selectivamente el colorante rojo Congo incorporado en el medio sólido. Ocho de las 15 cepas patógenas de E. coli (antígenos somáticos tipos O1, O78, O11 y OX9) absorbieron el colorante y produjeron colonias rojas entre las 48 y 72 horas de incubación. Todas las cepas de E. coli que poseían el antígeno O78 fueron rojo Congo positivas y las que poseían el antígeno O2 fueron rojo Congo negativas (colonias blancas). Cinco de las seis cepas apatógenas de E. coli también resultaron ser rojo Congo positivas. Sin embargo, a diferencia de las E. coli patógenas, las cepas apatógenas absorbieron el colorante tempranamente, es decir, entre las 18 a 24 horas de incubación. Aunque la absorción de rojo Congo no estuvo bien correlacionada con la patogenicidad, puede representar una propiedad identificable en algunos serotipos de E. coli.

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